An electrical power transmission network delivering electricity to consumers has to be able to handle voltage imbalances or instabilities, voltage sags, poor power factor, distortion, or flicker occurring within the network. Reactive power control is one way to resolve such problems.
A static synchronous compensator (STATCOM) is an electrical device, which is based on voltage source converter (VSC) technology, and which can be used to provide reactive power support to a power transmission network. It is capable of producing or absorbing reactive power and can be adjusted by a high-speed control system. A STATCOM may act as either a source or sink of reactive AC power to an electricity network. If the VSC is connected to a source of power such as battery, solar or wind generator, a STATCOM may also inject real AC power into the AC system. The STATCOM is a member of the flexible alternating current transmission system (FACTS) family of devices.
A STATCOM works by generating an AC current waveform leading or lagging the AC voltage, hence providing either inductive to capacitive reactive power. If it is inductive, the STATCOM can absorb reactive AC power. If it is capacitive, the STATCOM can generate reactive AC power. In this way, the STATCOM can function as a reactive power source or sink. The control of the reactive power is achieved by controlling the amplitude of the VSC converter voltage in respect to the grid voltage.
Since a typical VSC generates much lower voltage than grid voltage, there is a need to have a transformer between the VSC and the grid in a typical STATCOM system to match the voltage difference between the VSC and the electric grid. As an example, a typical STATCOM is depicted in FIG. 7.
It is desired to reduce costs associated with STATCOMs. It is also desired to improve performance of STATCOMs.